Switching valve

ABSTRACT

A switching valve for high pressure environments in selectively controlling fluid flow between three or more fluid passages included in the valve. The valve includes a body having a bore extending therethrough, a portion of the bore defining a valve chamber having opposed valve seats disposed at each end thereof. An elongated operating stem includes a valve plug at one end thereof for selective reciprocal movement in the chamber to block fluid flow through one of the seats and into or out of the chamber. The first fluid passage extends through the valve body into the bore adjacent one of the valve seats, the second fluid passage extends through the valve body into the chamber and the third fluid passage extends into the bore adjacent the other of the valve seats. In one end position of the stem, fluid flow is permitted between the first and second passages while in the other end position of the stem, fluid flow is permitted between the second and third fluid passages. For manual operation, a new stem design protects the integrity of the stem seals during assembly and disassembly of the valve and the valve seat disposed in the lowermost end of the bore is reversible and easily removable to provide a longer effective life therefor.

United States Patent [191 Bedo et al.

[ Dec. 31, 1974 1 SWITCHING VALVE [75] Inventors: Alfred Bedo, WaltonHills; Edward Beck, Cleveland Heights, both of Ohio [73] Assignee:Sno-Trik Company, Solon, Ohio [22] Filed: May'7, 1973 21 Appl. No.:357,558

[52] US. Cl 137/625.27, 251/214, 277/112 [51] Int. Cl. Fl6k 11/04 [58]Field of Search..... 137/625.27, 329.03, 625.65, 137/625.25, 392.02,243.3, 331, 270;

[56] References Cited UNITED STATES PATENTS 1,995,395 3/1935 Mohr251/214 X 2,123,814 7/1938 Summers 137/625.27 2,154,477 4/1939 Sinclairl37/625.27 X

2,260,523 10/1941 Henry 137/625.27 2,883,145 4/1959 Sage 251/214 X3,233,863 2/1966 Bowen et a1..... 251/214 X 3,237,917 3/1966 Kunzer eta1. 251/214 3,529,805 9/1970 Callahan, Jr. et a1 251/214 X 3,727,6314/1973 Suezawa 137/625.27

Primary ExaminerMartin P. Schwadron Assistant Examiner-Robert J. MillerAttorney, Agent, or FirmFay & Sharpe 5 7 ABSTRACT A switching valve forhigh pressure environments in selectively controlling fluid flow betweenthree or more fluid passages included in the valve. The valve includes abody having a bore extending therethrough, a portion of the boredefining a valve chamber having opposed valve seats disposed at each endthereof. An elongated operating stem includes a valve plug at one endthereof for selective reciprocal movement in the chamber to block fluidflow through one of the seats and into or out of the chamber. The firstfluid passage extends through the valve body into the bore adjacent oneof the valve seats, the second fluid passage extends through the valvebody into the chamber and the third fluid passage extends into the boreadjacent the other of the valve seats. In one end position of the stem,fluid flow is permitted between the first and second passages while inthe other end position of the stem, fluid flow is permitted between thesecond and third fluid passages. For manual operation, a new stem designprotects the integrity of the stem seals during assembly and disassemblyof the valve and the valve seat disposed in the lowermost end of thebore is reversible and easily removable to provide a longer effectivelife therefor.

13 Claims, 7 Drawing Figures SWITCHING VALVE BACKGROUND OF THE INVENTIONThis invention pertains to the art of valves and more particularly toswitching valves.

The invention is particularly applicable to switching fluid flow forcontrolling check or safety valves in high pressure environments such asoil wells and the like and will be described with particular referencethereto; however, it will be appreciated by those skilled in the artthat the invention has broader applications and may be used in otherenvironments where use of switching valves for controlling fluid floware particularly desired.

Prior switching valves of this type have generally comprised complexstructures requiring substantial initial expense. Because of thecomplexity of such prior switching valves, undesired premature valvefailure have oftentimes been a problem inasmuch as they added furtherexpense by way of maintenance and/or replacement costs. Also, priorvalves of this type in which an elongated valve stem has been employedto effect valve switching have not provided means for the integrity ofthe stem sealing arrangement when the stem was passed therethroughduring valve assembly and disassembly. Likewise, prior valves of thistype have not been particularly reliable for continuous use in highpressure environments.

The present invention contemplates a new and improved arrangement whichovercomes these problems and others and provides a new switching valveparticularly adapted for use in high pressure environments which issimple, economical, reliable and readily adaptable to use in variousdifferent applications and for either manual or automatic switching.

The principal object of the present invention is the provision of a newswitching valve which is simple in design and operation.

Another object of the present invention is the provision of a newswitching valve particularly adapted for use in high pressure fluidsystems.

Another object of the present invention is the provision of a newswitching valve which is adaptable for either manual or automaticenergization.

Still another object of the present invention is the provision of a newswitching valve having at least one of the valve seats which isreversible.

Yet another object of the present invention is the provision of a newswitching valve which includes a stemdesign for protecting the integrityof the stem sealing medium during assembly and disassembly of the valve.

Yet a further object of the present invention is the provision of a newswitching valve having a high degree of reliability during continuoushigh pressure usage.

A further object of the present invention is the provision of a newswitching valve which may be operated as either a normally open ornormally closed valve.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the presentinvention, there is provided a valve for controlling fluid flow betweenthree or more separate flow passages. The valve structure has a valvebody including an elongated bore extending therethrough, a portion ofthe bore defining a generally cylindrical valve chamber. First andsecond axially aligned valve seats, including fluid openingstherethrough, are disposed in the bore adjacent one end thereof todefine first and second axially spaced ends of the chamber. A firstfluid flow passage extends between the exterior of the valve body andthe side wall of the bore adjacent the first end, a second fluid flowpassage extends between the exterior of the valve body and the side wallof the valve chamber and a third fluid flow passage extends between theexterior of the valve body and the side wall of the bore adjacent thesecond end. A valve operating stem extends axially into the valvechamber through the first valve seat and the stem is dimensioned so asto provide a substantial flow area through the first valve seat into thechamber about the stem. The valve stem further includes a valve plugdisposed in the chamber adjacent the end of the stem and comprises aunitary body having opposed, generally conically shaped end portions anda cylindrical center section with the diameter of the center sectionbeing greater than the diameter of the flow openings in the first andsecond seats. Means are included for selectively reciprocating the stembetween a first position with a valve plug in a fluid flow blockingrelationship with the fluid flow passage of the first seat to permitfluid flow between the second and third fluid flow passages and a secondposition with the valve plug in a fluid flow blocking relationship withthe fluid flow passage of the second seat to permit fluid flow betweenthe first and second fluid flow passages. The valve also includes asealing structure, a packing nut and a liner sleeve disposed in theother end of the bore from the chamber which accommodate thereciprocating means and provide a fluid seal therefor.

In accordance with another aspect of the present invention, thereciprocating means comprises a handle having a shaft extending throughthe packing nut to be threadedly received on the inside of the linersleeve. The connection between the stem and shaft permit relativerotation therebetween whereby as the stem is threadedly moved relativeto the liner, the stem only realizes reciprocating movement between thefirst and second positions.

In accordance with another aspect of the present invention, thereciprocating means comprise power means selectively energizable to movethe stem between the first and second positions. In this instance, thestem is threadedly mounted to the power means within the liner sleeve.

In accordance with still another aspect of the present invention, thesecond valve seat is included in a member which is selectively removablefrom within the bore at the one end of the valve body. This member isreversible for reinsertion into the bore so as to present another secondvalve seat.

In accordance with still another aspect of the present invention, thereis provided a new valve stem having a dimensional configuration of atype which protects the integrity of the sealing medium. When using thisnew stem, the valve may be assembled or disassembled by having the stempass through the sealing mechanism out of the third fluid passagewithout stretching or otherwise undesirably deforming the medium.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may take physical formin certain parts and arrangements of parts, a preferred embodiment ofwhich will be described in detail in the specification and illustratedin the accompanying drawings which form a part thereof and wherein:

FIG. 1 is a partial cross-sectional view of a manually operatedswitching valve incorporating the concepts of the invention;

FIG. 2 is an enlarged view of a portion of the valve of FIG. 1 showingparticularly the inner workings of the valve itself;

FIG. 3 is an enlarged view of the valve plug in one operative position;

FIG. 4 is an enlarged view of the valve plug in the other operativeposition;

FIG. 5 is an enlarged view of the operating valve stem;

FIG. 6 is a partial cross-sectional view of a second embodiment of thesubject invention employing automatic energization means; and,

FIG. 7 is an enlarged view of a portion of the inner workings of thevalve shown in FIG. 6.

Referring now to the drawings wherein the drawings are for purposes ofillustrating the preferred embodiment of the invention only and not forpurposes of limiting means, the FIGURES show a valve body A, valveworkings B and a valve operator C. Certain of the component structuresemployed in practicing the present invention are shown in the commonlyassigned US. Pat. No. 3,679,169, which showings and teachings areincorporated herein by reference.

More specifically, and with principal reference to FIGS. 1 and 2, thevalve body includes a generally elongated body portion 10 having a topend 12, a bottom end 14 and continuous side wall 16. Extendinglongitudinally through body 10 is a bore having various diameterportions axially spaced therealong for reasons which will hereinafterbecome apparent. A portion of bore 20 adjacent bottom end 14 acts todefine a valve chamber 22 having first valve seat 24 and a second valveseat 26 which are opposed to and axially spaced apart from each other inorder to define the ends of chamber 22.

Extending through the valve body is a first fluid flow passage 30communicating with bore 20 on the other side of first valve seat 24 fromchamber 22. A second fluid flow passage 32 extends through the valvebody into the valve chamber itself and finally, a third fluid flowpassage 34 extends through the valve body at bottom end 14 on the otherside of second valve seat 26 from chamber 22. Protruding outwardly fromside wall 16 at the exit area of passages 30,32 are outwardly threadedmembers 36,38 respectively adapted to receive conventional fluidcouplings or fittings thereon in order that the valve may beconveniently incorporated into a fluid system. These threaded membersalso include conventional openings (not shown) therein for receiving theends of tubing for coupling purposes. Inasmuch as these features areknown and do not form a part of the present invention, they are notdiscussed in detail herein. Bore 20, adjacent bottom end 14, includes anenlarged threaded area 42 adapted to receive a threaded fitting 44. Thisfitting includes an outer threaded end similar to the arrangement ofmembers 36,38 which is also employed for receiving conventionalcouplings or fittings. Although the valve body could be constructed fromseveral materials, an austenitic stainless steel is preferred.

Second valve seat 26 is included in a separate second seat member 50having opposed frusto-conical ends 52,54 and a generally cylindricalcenter portion 56. A fluid opening 58 connects ends 50,54 and the endface of each end comprises a separate second valve seat. Thus, thisarrangement facilitates ready replacement of the second valve seat bymerely reversing the position of second seat member as will hereinafterbe more fully described. Although the seat member may be comprised ofany number of materials without departing from the intent and scope ofthe invention, austenitic stainless steel is particularly preferred. Toaccommodate and properly locate one of frusto-conical ends 52,54relative to the valve body, there is provided a frusto-conical area 60connecting enlarged threaded area 42 of bore 20 and valve chamber 22.Likewise, threaded fitting 44 includes an inwardly extending chamber toclosely receive the other of the frusto conical ends 52,54 and thegenerally cylindrical center portion 56 of the seat member.

Adjacent first valve seat 24, bore 20 has a smaller diameter portionextending a short axial distance and which then expands into a slightlylarger diameter por tion 72 to define a sealing medium receiving area.Adjacent the end of this larger diameter portion and spaced toward topend 12 is an outwardly flaring or frusto-conical surface portion 74which then is connected to an even larger, partially threaded packingnut receiving portion 76. The effect and use of bore portions 70,72, 74and 76 will become apparent hereinafter.

Disposed within bore 20 for selective reciprocation therein to effectthe switching operation of the valve is a valve operating stem generallydesignated in FIG. 1. FIGS. 2 and 5 show the stem in greater detail andas comprising a unitary structure having an enlarged mounting portion92, an intermediate portion 94 and a valve plug 96. Disposed betweenmounting portion 92 and intermediate portion 94 is a first connectingportion 98 and disposed between intermediate portion 94 and valve plug96 is a second connecting portion 100. In the embodiment of the presentinvention here under discussion, the diameters of the connectingportions are less than the diameter of portions 92,94 and plug 96. Valveplug 96 includes opposed conical ends 102,104 connected by a generallycylindrical center portion 106. The two conical portions, in conjunctionwith seats 24,26 effect the desired switching during valve operation aswill become apparent. In this embodiment of the present invention,enlarged stem mounting portion 92 comprises a generally sphericalconfiguration having a reduced diameter area or band extending generallycentrally therearound. Also, the diameter of intermediate portion 94 isat least equal to the greatest cross-sectional dimension of sphericalarrangement 108 to receive the desired operating stem properties.Although a martensitic stainless steel stem construction is preferred,other materials may be employed without departing from the scope andintent of the invention.

Disposed in larger diameter sealing medium receiving portion 72 is aseal washer 120. This washer is generally annular shaped having anoutside diameter slightly less than the diameter of bore 72 and aninside diameter slightly in excess of the outside diameter of stemintermediate portion 94. A sealing member 122 is received in bore 72adjacent washer 120. In the preferred embodiment of the invention, thismember is manufactured from glass filled TEFLON, is generally annularshaped and has an outside diameter slightly less than the diameter ofbore 72 with an internal diameter slightly larger than the outsidediameter of stem intermediate portion 94.

An alignment bushing 124 includes a forward portion 126 having anoutside diameter slightly less than the diameter of bore 72 and aninternal passageway having a diameter slightly in excess of the outsidediameter of stem intermediate portion 94. The'alignment bushing alsoincludes a flange portion 128 defining a thrust surface 130 which liesin a plane generally transverse to the axis of bore 20. Flange portion128 is connected to forward portion 126 by a generally frusto-conicalsurface 132. In the preferred embodiment of the invention, seal washer120 and alignment bushing 124 are constructed from stainless steel;however, it will be appreciated that other materials may be employed.

A packing nut 140 having a generally cup-like configuration is receivedin enlarged diameter portion 76 of bore adjacent top end 12.Specifically, this nut includes an outer peripheral surface 142 having aplurality of threads 144 extending axially therealong over a portionthereof from the open end toward the closed or top wall 146. Threads 144engage corresponding threads extending inwardly along bore 76 from topend 12. The packing nut includes a passageway 148 extending through topwall 146 and the top wall itself defines an internal shoulder 150.Packing nut 140 includes the conventional external hex configurationwhich is adapted to be engaged by a tool or other suitable instrumentfor purposes of rotating the packing nut relative to the valve body. Thelower extremity of the packing nut, that is, the open end of thecup-like configuration, defines a driving surface which lies in a planegenerally parallel to .alignment bushing thrust surface 130. A keeper152 suitably operates against the outer hex configuration in order toretain the nut in position. The keeper thus prohibits undesired rotationof the packing nut in a manner once the required compressive force hasbeen applied to sealing member 122.

Disposed within the packing nut and cooperating therewith is a linersleeve 160. This liner sleeve includes a bore 162 including a pluralityof threads 164 spaced axially therealong from the uppermost end towardthe lowermost end. The liner sleeve is generally cylindrical and isadapted to be received within packing 140 with the uppermost end portionof the sleeve engaging shoulder 150 of the nut. The very precise packingnut and liner sleeve structure, as well as means for venting fluidleakage past the sealing member will be appreciated from the teachingsof the US. Pat. No. 3,679,l69, the teachings of which are incorporatedherein by reference.

An actuating stem or shaft 170 having a conventional handle 174 isprovided for operating the valve. This stem or shaft includes threadsdisposed partially therealong which are adapted to mate with threads 164of liner sleeve 160 as will hereinafter be more fully described.Disposed on the other end of actuating stem 170 from handle 174 is anenlarged actuating stem receiving portion 178 including a stem receivingand mounting area 180 therein. A retaining ring 182 is employed to lockmounting portion 92 of operating stem 90 in position in area 180 toeliminate axial movement between the two stems while permitting relativerotation between them. The specifics of the mounting arrangement,particularly area 180, may be more readily seen from the teachings ofthe US. Pat. No. 3,679,169.

In the embodiment of the invention under discussion, liner sleeve isconstructed from brass or other similar material and the packing nut andactuating stem or shaft are constructed from stainless steel. Such anarrangement tends to. reduce galling of the threaded connection betweenthe stem and packing nut under high pressure conditions although it willbe appreciated that other materials could be employed.

Valve body 10 may be conveniently located to a base plate 190 or thelike by bolts 192,194 as is also deemed conventional.

In operation and with the valve conveniently mounted to a base portion190 by, for example, bolts 192,194 and the necessary fluid linesconnected to passages 30,32 and 34, there are two primary or endpositions for valve plug 96 to effect the switching operation. The firstposition shown in FIG. 3, with conical end 102 closely received againstfirst valve seat 24, permits fluid flow only between second and thirdfluid passages 32,34. By rotating handle 174 to threadedly advance stemor shaft relative to liner sleeve 160, valve plug 96 is moved toward thesecond position shown in FIG. 4. In this position, conical end 104engages second valve seat 26 to permit fluid flow only between first andsecond passages 30,32. Return to the first position is effected bythreadedly retracting stem 170 relative to the liner sleeve. Theconnection between actuating stem or shaft 170 and operating stem 90 issuch that the rotating movement of the actuating stem encountered duringits threaded movement causes only reciprocating movement of operatingstem 90. This, of course, is because of the particular connectionbetween stems 90,170. It is important that the valve plug does notrotate during switching between the end positions in order to preservethe integrity of seats 24,26.

A particularly advantageous use for the subject switching valve, andmerely by way of example only, is in oil well safety valve applications.In such applications, a ball check or safety valve is disposed at thebase of the oil well shaft itself. This ball check or safety valve is ina normally open position in order that petroleum from the well may flowoutward therefrom for normal recovery. To operate the ball check valveusing the switching valve of the subject invention, fluid flow passage30 is connected to a high pressure fluid source. Fluid flow passage 32is then connected by remote fluid circuit with the ball check or safetyvalve and fluid flow passage 34 is connected to exhaust. When the oilwell is operating normally, the switching valve plug is maintained inthe first end position with conical end 102 blocking fluid flow betweenthe first fluid flow passage 30 to second fluid flow passage 32. If,however, the well should catch on fire or it be otherwise desired toshut off the flow of petroleum upward through the well, the valve plugis moved to the second end position wherein conical end 104 engagessecond valve seat 26 so as to block fluid flow between passages 32,34and permitting flow between passages 30,32. The fluid under highpressure from a source (not shown) passes through passage 30 to passage32 and then downwardly into the well, thence overcoming any forcemaintaining the ball check or safety valve in an open condition in orderto close that valve. This closing thereby shuts off the petroleum flowto preserve petroleum in the well from loss and, in the case of a fire,eliminates the fuel source as the fire burns itself out.

If the second valve seat should become worn during continuous operation,it is merely necessary to remove threaded fitting 44 from its threadedconnection with the valve body, remove second seat member 50 from thebody, turn it around and reinsert it in order to present a new secondseat. This, of course, makes the valve more versatile in not having toreplace a separate seat member each time the second seat becomes worn.

When it is desired to replace or otherwise remove operating stem 90 fromthe valve, it is merely necessary to remove packing nut 140 and linersleeve 160 from their threaded association with the valve body.Thereafter, retaining ring 182 may be removed from stem 170 so thatoperating stem 90 and actuating stem 170 may be separated similar to themanner explained in US. Pat. No. 3,679,169. Once the two stems areseparated, operating stem 90 may be pulled outwardly through bore 20from bottom end 14. Reassembly of the valve is then performed in anopposite manner to that just hereinabove described for disassembly. Itshould be noted here that stem intermediate portion 94 acts to protectthe integrity of sealing medium. As the operating stem is removed fromor inserted into the valve, spherical arrangement 108 normally has atendency to slightly temporarily deform the sealing medium, that is,sealing member 122 on its passage therethrough. Because of thisdeformation, there is a possibility that fluid leaks could result sothat fluid is permitted to undesirably pass between the stern andsealing medium. Although means are provided to handle a small amount ofsuch leakage inherent when using such sealing mediums, any increase inthe leakage can affect valve effectiveness. However, with intermediatestem portion 94 of the present embodiment being at least the samecross-sectional dimension as the largest crosssectional dimension ofspherical arrangement 108, this particular problem is overcome. Further,intermediate portion 94 has an axial length at least sufficient to be incontinuous contact with seal washer 120, sealing member 122 andalignment bushing 124 during valve operation to assure good sealing.

An alternative arrangement to that hereinabove described with referenceto FIGS. lis the arrangement shown in FIGS. 6 and 7 for a poweractivated valve. Inasmuch as substantially all the component parts ofthe FIGS. 6 and 7 embodiment are identical to the FIGS. 1-5 embodiment,identical numerals with a prime suffix will be employed with new partsor components having new numerals. In this arrangement, operating stem90' includes a generally hexagonal center portion 200 to facilitate easeof stem removal as will hereinafter become apparent. Although valve plug96' is substantially identical with valve plug 96, in this secondembodiment, operating stem 90' has an operating stern shaft 202 of aconstant cross-section. Adjacent the other end of the stem shaft fromthe valve plug is a threaded area 204 for connecting the operating stemto actuating stem 170. Liner 160 includes an enlarged stem receivingportion 206 at the base of actuating stem or shaft 170 which, in turn,is connected to valve operator C. Threaded portion 204 is closelythreadedly received in receiving portion 206 but in this embodiment norelative rotation is permitted between stems 90', 170'. Stem 170'includes a conventional connection generally designated 208 to apneumatic drive valve generally designated 212 which may be energized asdesired in order to switch the operating stern and valve plug betweenthe first and second end positions. Drive valve 212 may, of course, beenergized from a remote station if so desired. Inasmuch as when usingthis arrangement actuator stem 170 only received reciprocal movement, itis not necessary to include that structure facilitating relativerotational movement between stems 170 and in order to protect the valveseats during valve operation. Although a pneumatic drive valve 212energizing arrangement has been disclosed, it will be appreciated byothers skilled in the art that alternative drive mediums may be employedwithout departing from the intent and scope of the present invention.

When it is desired to remove operating stem 90' from association withthe valve body, it is merely necessary to first remove threaded fitting44' and second seat member 50' from their association with the valvebody as hereinabove described. Since the valve plug includes a generallyhexagonal center portion 200, it is then merely necessary to insert awrench into the longitudinally extending bore 20 and turn the stem torelease it from its threaded connection with member 206. Reassembly ofthe stem into the valve is accomplished in an opposite manner from thatjust described with reference to disassembly.

It should be recognized that the valve hereinabove described is notintended to be limited in scope of usage. Thus, the valve may be used aseither normally open or normally closed in order to effect the desiredswitching in any type of high pressure fluid environment.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon the reading and understanding of the specification. It isour intention to include all such modifications and alterations insofaras they come within the scope of the appended claims or the equivalentsthereof.

Having thus described our invention, we now claim:

1. A switching valve for controlling fluid flow between three separatefluid flow passages, said valve comprising:

a valve body including an elongated bore extending therethrough, aportion of said bore adjacent one end thereof defining a generallycylindrical valve chamber;

first and second axially aligned valve seats including fluid openingstherethrough disposed in said bore to define first and second axiallyspaced ends for said chamber;

a first fluid flow passage extending between the exterior of said valvebody and the side wall of said bore adjacent said first end;

a second fluid flow passage extending between the exterior of said valvebody and the side wall of said valve chamber;

a third fluid flow passage extending between the exterior of said valvebody and the side wall of said bore adjacent said second end;

a valve operating stem extending axially into said valve chamber throughsaid first valve seat, said stem being dimensioned to provide asubstantial flow area through said first valve seat and into saidchamber about said stem, said valve stem further including a valve plugdisposed in said chamber adjacent the end of said stem, said valve plugcomprising unitary body having opposed, generally conically shaped endportions and a cylindrical center section being greater than thediameter of the fluid openings of said first and second seats;

means for selectively reciprocating said stem between a first seatedposition with said valve plug in a fluid flow blocking relationship withthe fluid opening of the first seat to permit fluid flow between saidsecond and third fluid flow passages and a second seated position withsaid valve plug in a fluid flow blocking relationship with the fluidopening of said second seat to permit fluid flow between said first andsecond fluid flow passages,

a sealing washer received in said bore on the other side of said firstfluid passage from said first valve seat, said washer having a boretherethrough slightly larger than the diameter of said stem;

a sealing member closely received over said stem and spaced outwardlyalong said bore adjacent said sealing washer;

a bushing received oversaid stern and spaced outwardly along said boreadjacent said sealing memher;

a packing nut threadedly received in said bore adjacent the other endthereof from said bore one end, said nut adapted to contact said bushingand to apply a compressive force to said sealing member; and,

a liner sleeve disposed in said packing unit, said liner sleeve housingthe connection between said operating stem and said reciprocating means.

2. The valve as defined in claim 1 wherein said reciprocating meanscomprises a handle including a shaft extending through said packing nutwith said shaft being threadedly received on the inside of said linersleeve, said connection permitting relative rotation between said shaftand stem, whereby as said stem is threadedly moved relative to saidliner, said stem substantially only realizes reciprocating movementbetween said first and second positions.

3. The valve as defined in claim 2 wherein the end of said shaftincludes means defining an inwardly extending stem receiving area withsaid stem including a generally spherical mounting area at its outermostend, said stem receiving area being dimensioned to receive said mountingarea in a rotatable relationship relative thereto and to prevent axialmovement between said stem and said shaft.

4. The valve as defined in claim 3 further including releasable meansfor retaining said spherical mounting area in said stem receiving area.

5. The valve as defined in claim 3 wherein said stem includes saidspherical area at one end, said valve plug at the other end and anintermediate working portion disposed therebetween, said intermediateportion having a cross-sectional dimension at least as large as thediameter of said stem mounting area.

6. The valve as defined in claim 5 wherein said stern further includesconnecting portions disposed between said intermediate portion and saidstem mounting area and between said intermediate portion and said valveplug, said connecting portions having cross-sectional dimensions lessthan said intermediate working portions with said intermediate portionhaving an axial length sufficient to permit continuous engagement withsaid sealing washer, sealing member and bushing during travel of saidstern between said first and second positions.

7. The valve as defined in claim 1 wherein said second valve seat isselectively removable from said bore from said one end thereof.

8. The valve as defined in claim 7 wherein said second valve seatcomprises a separate seat member having a second valve seat in each endface thereof, said second valve seats in said member being connected bysaid second seat fluid opening.

9. The valve as defined in claim 1 wherein said reciprocating meanscomprises power means selectively energizable to move said stem betweensaid first and second position.

10. The valve as defined in claim 9 wherein said power means includes astem receiving member extending through said packing nut into said linersleeve with said stem threadedly engaging said stem receiving member atthe other end thereof from said valve plug, said valve stem having asubstantially constant cross section over the entire length thereof fromsaid valve plug.

11. A switching valve for controlling fluid flow between three separatefluid flow passages, said valve comprising:

a valve body including an elongated bore extending therethrough, aportion of said bore adjacent one end thereof defining a generallycylindrical valve chamber;

first and second axially aligned valve seats including fluid openingstherethrough disposed in said bore to define first and second axiallyspaced ends for said chamber;

a first fluid flow passage extending between the exterior of said valvebody and the side wall of said bore adjacent said first end;

a second fluid flow passage extending between the exterior of said valvebody and the side wall of said valve chamber;

a third fluid flow passage extending between the exte rior of said valvebody and the side wall of said bore adjacent said second end;

a valve operating stem extending axially into said valve chamber throughsaid first valve seat, said stem being dimensioned to provide asubstantial flow area through said first valve seat and into saidchamber about said stem, said valve stem further including a valve plugdisposed in said chamber adjacent the end of said stem, said valve plugcomprising a unitary body having opposed, generally conically shaped endportions and a cylindrical center section with the diameter of saidcenter section being greater than the diameter of the fluid openings ofsaid first and second seats;

means for selectively reciprocating said stem between a first seatedposition with said valve plug in a fluid flow blocking relationship withthefluid opening of the first seat to permit fluid flow between saidsecond and third fluid flow passages and a second seated position withsaid valve plug in a fluid flow blocking relationship with the fluidopenings of said second seat to permit fluid flow between said first andsecond fluid flow passages; and,

means for sealing and means for closing the other end of said bore toeliminate fluid flow outwardly of means being housed in said linersleeve.

12. The valve as defined in claim 11 wherein said reciprocating meansextends through said packing nut into said liner sleeve.

13. The valve as defined in claim 12 wherein said reciprocating means isthreadedly received in said liner sleeve and said connection facilitatesrelative rotation between said stem and reciprocating means whereby assaid reciprocating means is threadedly moved relative to said liner,only reciprocating movement is transmit-

1. A switching valve for controlling fluid flow between three separatefluid flow passages, said valve comprising: a valve body including anelongated bore extending therethrough, a portion of said bore adjacentone end thereof defining a generally cylindrical valve chamber; firstand second axially aligned valve seats including fluid openingstherethrough disposed in said bore to define first and second axiallyspaced ends for said chamber; a first fluid flow passage extendingbetween the exterior of said valve body and the side wall of said boreadjacent said first end; a second fluid flow passage extending betweenthe exterior of said valve body and the side wall of said valve chamber;a third fluid flow passage extending between the exterior of said valvebody and the side wall of said bore adjacent said second end; a valveoperating stem extending axially into said valve chamber through saidfirst valve seat, said stem being dimensioned to provide a substantialflow area through said first valve seat and into said chamber about saidstem, said valve stem further including a valve plug disposed in saidchamber adjacent the end of said stem, said valve plug comprisingunitary body having opposed, generally conically shaped end portions anda cylindrical center section being greater than the diameter of thefluid openings of said first and second seats; means for selectivelyreciprocating said stem between a first seated position with said valveplug in a fluid flow blocking relationship with the fluid opening of thefirst seat to permit fluid flow between said second and third fluid flowpassages and a second seated position with said valve plug in a fluidflow blocking relationship with the fluid opening of said second seat topermit fluid flow between said first and second fluid flow passages, asealing washer received in said bore on the other side of said firstfluid passage from said first valve seat, said washer having a boretherethrough slightly larger than the diameter of said stem; a sealingmember closely received over said stem and spaced outwardly along saidbore adjacent said sealing washer; a bushing received over said stem andspaced outwardly along said bore adjacent said sealing member; a packingnut threadedly received in said bore adjacent the other end thereof fromsaid bore one end, said nut adapted to contact said bushing and to applya compressive force to said sealing member; and, a liner sleeve disposedin said packing unit, said liner sleeve housing the connection betweensaid operating stem and said reciprocating means.
 2. The valve asdefined in claim 1 wherein said reciprocating means comprises a handleincluding a shaft extending through said packing nut with said shaftbeing threadedly received on the inside of said liner sleeve, saidconnection permitting relative rotation between said shaft and stem,whereby as said stem is threadedly moved relative to said liner, saidstem substantially only realizes reciprocating movement between saidfirst and second positions.
 3. The valve as defined in claim 2 whereinthe end of said shaft includes means defining an inwardly extending stemreceiving area with said stem including a generally spherical mountingarea at its outermost end, said stem receiving area being dimensioned toreceive said mounting area in a rotatable relationship relative theretoand to prevent axial movement between said stem and said shaft.
 4. Thevalve as defined in claim 3 further including releasable means forretaining said spherical mounting area in said stem receiving area. 5.The valve as defined in claim 3 wherein said stem includes saidspherical area at one end, said valve plug at the other end and anintermediate working portion disposed therebetween, said intermediateportion having a cross-sectional dimension at least as large as thediameter of said stem Mounting area.
 6. The valve as defined in claim 5wherein said stem further includes connecting portions disposed betweensaid intermediate portion and said stem mounting area and between saidintermediate portion and said valve plug, said connecting portionshaving cross-sectional dimensions less than said intermediate workingportions with said intermediate portion having an axial lengthsufficient to permit continuous engagement with said sealing washer,sealing member and bushing during travel of said stem between said firstand second positions.
 7. The valve as defined in claim 1 wherein saidsecond valve seat is selectively removable from said bore from said oneend thereof.
 8. The valve as defined in claim 7 wherein said secondvalve seat comprises a separate seat member having a second valve seatin each end face thereof, said second valve seats in said member beingconnected by said second seat fluid opening.
 9. The valve as defined inclaim 1 wherein said reciprocating means comprises power meansselectively energizable to move said stem between said first and secondposition.
 10. The valve as defined in claim 9 wherein said power meansincludes a stem receiving member extending through said packing nut intosaid liner sleeve with said stem threadedly engaging said stem receivingmember at the other end thereof from said valve plug, said valve stemhaving a substantially constant cross section over the entire lengththereof from said valve plug.
 11. A switching valve for controllingfluid flow between three separate fluid flow passages, said valvecomprising: a valve body including an elongated bore extendingtherethrough, a portion of said bore adjacent one end thereof defining agenerally cylindrical valve chamber; first and second axially alignedvalve seats including fluid openings therethrough disposed in said boreto define first and second axially spaced ends for said chamber; a firstfluid flow passage extending between the exterior of said valve body andthe side wall of said bore adjacent said first end; a second fluid flowpassage extending between the exterior of said valve body and the sidewall of said valve chamber; a third fluid flow passage extending betweenthe exterior of said valve body and the side wall of said bore adjacentsaid second end; a valve operating stem extending axially into saidvalve chamber through said first valve seat, said stem being dimensionedto provide a substantial flow area through said first valve seat andinto said chamber about said stem, said valve stem further including avalve plug disposed in said chamber adjacent the end of said stem, saidvalve plug comprising a unitary body having opposed, generally conicallyshaped end portions and a cylindrical center section with the diameterof said center section being greater than the diameter of the fluidopenings of said first and second seats; means for selectivelyreciprocating said stem between a first seated position with said valveplug in a fluid flow blocking relationship with the fluid opening of thefirst seat to permit fluid flow between said second and third fluid flowpassages and a second seated position with said valve plug in a fluidflow blocking relationship with the fluid openings of said second seatto permit fluid flow between said first and second fluid flow passages;and, means for sealing and means for closing the other end of said boreto eliminate fluid flow outwardly of said valve through said borebetween said operating stem and reciprocating means, said sealing meanscomprising a sealing medium received in said bore on the other side ofsaid first fluid passage from said first valve seat and said closingmeans comprising a packing nut threadedly received in said bore adjacentthe other end thereof from said one end, said packing nut adapted tocontact said sealing medium and supply a compressive force thereagainst,said packing nut further including a liner sleeve received thereIn, theconnection between said operating stem and said reciprocating meansbeing housed in said liner sleeve.
 12. The valve as defined in claim 11wherein said reciprocating means extends through said packing nut intosaid liner sleeve.
 13. The valve as defined in claim 12 wherein saidreciprocating means is threadedly received in said liner sleeve and saidconnection facilitates relative rotation between said stem andreciprocating means whereby as said reciprocating means is threadedlymoved relative to said liner, only reciprocating movement is transmittedto said stem.